Manufacturing apparatuses for the deposition of a material on a carrier body are known in the art. Such manufacturing apparatuses comprise a housing that defines a chamber. Generally, the carrier body is substantially U-shaped having a first end and a second end spaced from each other. Typically, a socket is disposed at each end of the carrier body. Generally, two or more electrodes are disposed within the chamber for receiving the respective socket disposed at the first end and the second end of the carrier body, respectively. The electrode also includes a contact region, which supports the socket and, ultimately, the carrier body to prevent the carrier body from moving relative to the housing. The contact region is the portion of the electrode adapted to be in direct contact with the socket and that provides a primary current path from the electrode to the socket and into the carrier body.
A power supply device is coupled to the electrode for supplying an electrical current to the carrier body. The electrical current heats both the electrode and the carrier body. The electrode and the carrier body each have a temperature with the temperature of the carrier body being heated to a deposition temperature. A processed carrier body is formed by depositing the material on the carrier body.
As known in the art, variations exist in the shape of the electrode and the socket to account for thermal expansion of the material deposited on the carrier body as the carrier body is heated to the deposition temperature. One such method utilizes a flat head electrode and a socket in the form of a graphite sliding block. The graphite sliding block acts as a bridge between the carrier body and the flat head electrode. The weight of the carrier body and the graphite sliding block acting on the contact region reduces the contact resistance between the graphite sliding block and the flat head electrode. Another such method involves the use of a two-part electrode. The two-part electrode includes a first half and a second half for compressing the socket. A spring element is coupled to the first half and the second half of the two-part electrode for providing a force to compress the socket. Another such method involves the use of an electrode defining a cup with the contact region located within a portion of the cup. The socket is adapted to fit into the cup of the electrode and to contact the contact region located within the cup of the electrode. Alternatively, the electrode may define the contact region on an outer surface thereof without defining a cup, and the socket may be structured as a cap that fits over the top of the electrode for contacting the contact region located on the outer surface of the electrode.
A fouling of the electrode occurs on the exterior surface of the electrode outside of the contact region on the portion of the electrode that is disposed within the chamber due to the buildup of deposits. The deposits result in an improper fit between the socket and the electrode over time. The improper fit causes small electrical arcs between the contact region and the socket that result in metal contamination of the material deposited on the carrier body. The metal contamination reduces the value of the carrier body as the material deposited is less pure. Additionally, the fouling reduces the heat transfer between the electrode and the socket resulting in the electrode reaching higher temperatures to effectively heat the socket and ultimately the carrier body. The higher temperatures of the electrode result in accelerated deposition of the material on the electrode. This is especially the case for electrodes that comprise silver or copper as the sole or main metal present therein.
Additionally, a fouling of the electrode occurs on the exterior surface of the electrode, on the portion of the exterior surface that is outside of the chamber. Such fouling is different from the type of fouling that occurs on the portion of the electrode that is disposed within the chamber, which is attributable to the material used for deposition. The fouling of the exterior surface of the electrode that is outside of the chamber may be caused by industrial conditions outside of the manufacturing apparatus, or may merely be attributable to oxidation due to the exposure of the electrode to air. This is especially the case for electrodes that comprise silver or copper as the sole or main metal present therein.
The electrode must be replaced when one or more of the following conditions occur: first, when the metal contamination of the material being deposited upon the carrier body exceeds a threshold level; second, when fouling of the exterior surface of the electrode in the chamber causes the connection between the electrode and the socket to become poor; and third, when excessive operating temperatures for the electrode are required due to deposition of the material on the electrode. The electrode has a life determined by the number of the carrier bodies the electrode can produce before one of the above occurs.
In view of the foregoing problems related to fouling of the electrode, there remains a need to at least delay the fouling of the electrode to improve the productivity of the electrode and to thereby increase useful life of the electrode.